[Bug] Stdin freeze when pasting markdown table with pipe characters

Bug Description
Pasting a table with Unicode box-drawing characters (│ ─ ├ ┼ etc.)
freezes stdin when the table has 4+ rows. Works fine with 3 or fewer rows.
Unfreezes after copying and pasting something else.

Likely caused by multi-byte UTF-8 sequences (3 bytes each) exceeding stdin buffer boundary when pasting multiple consecutive lines.
Reproduction: copy any 4+ row box-drawing table → Cmd+V in Claude Code

Environment Info

• Platform: darwin
• Terminal: cursor
• Version: 2.1.72
• Feedback ID: 347e2814-f2f8-4f51-b165-25a27986c06d

Errors

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